We report two patients, mother and daughter, presenting a Marie Unna's syndrome and belonging to a family in which the disease appeared in seven members in a period of four generations. We point out the more frequent features of this syndrome: male pattern alopecia, rare hairs resembling a 'horse hair', and follicular atrophy. Scanning electron microscopy studies showed cuticular changes, transversal breaks, irregular shape, twistings and depressions of the hairs.